Communication terminals carried and used by persons have been known (refer to Patent Literature 1).
The communication terminal of this type periodically transmits position information indicative of a present position of the communication terminal to an in-vehicle communication device installed in a vehicle by wireless information communication.
Patent Literature 1: JP-2009-134363A
The inventor of the present application has found the followings concerning a communication terminal.
In the communication terminal of this type, because a battery is used as power supply, the consumption of electric power is required to be saved.
In order to satisfy this requirement, in the communication terminal disclosed in Patent Literature 1, if another communication terminal is present within an area where a signal can be received through short range wireless communication, the transmission of the position information from the communication terminal stops.
Incidentally, situations around the communication terminal are various. For example, in a specified area from the communication terminal, another communication terminal is not present or multiple other communication terminals are present. Among those situations, there is a situation in which transmission of the position information is considered to be unnecessary.
However, in the communication terminal disclosed in Patent Literature 1, because a condition for stopping the transmission of the position information is that another communication terminal is present within the specified area from the communication terminal, the position information is transmitted even in a situation where the transmission of the position information is considered to be unnecessary.
That is, the inventor of the present application has found that the conventional art is insufficient in implementation of both of the transmission of necessary position information and the saving of power consumption.